#!/usr/bin/env node 
const {Readable}=require('stream');
class MyReadable extends Readable{
  constructor(){
    super();
  }
}
_read(){
  this.push(String.fromCharCode(this.#c++))
    if (thi.#c>'z'.charCodeAt(0))this.push(null);
}
#c='a'.charCodeAt(0);
let res=new MyReadable();
res.pipe(process.stdout);

